Effect of MAC welding on microstructure and mechanical properties of dual phase steel

In this study, the effect of metal active gas (MAC) welding has been evaluated on the microstructural and mechanical properties of dual phase steel. Low carbon dual phase steels containing varying volume fraction of martensite was produced with coarse and fine microstructure. Specimens were joined by MAC welding method and tensile tests and microstructural analysis were performed on these specimens. Initial microstructure of steel plates appears to be a factor in determining the microstructure of heat affected zone (HAZ). Average grain size in MAC weld metal deposited on fine grained dual phase steels produced was in the range of 7.7 to 8.9 micron. Columnar grains with comparatively large average grain size were also observed in weld metals. Yield and maximum tensile strengths are relatively lower than those of non welded steels. Tensile strengths of weld metals (WM) deposited on initially coarse grained dual phase steels yielded better results than those with initially fine grained dual phase steels.